3com 3031 Instruccion De Instalación
396
C
HAPTER
31: IP P
ERFORMANCE
C
ONFIGURATION
Configuring Fast
Forwarding
Forwarding
Brief Introduction to
Fast Forwarding
Message forwarding efficiency is a key feature evaluating router performance.
According to regular flow, when a message arrives, the router will copy it from the
interface memory to the main CPU. The CPU specifies the network ID from the IP
address, consults with the routing table to get the best path to forward the
message, and creates MAC frame suitable for output of the message. The created
MAC frame is copied to the output queue via DMA (Direct Memory Access), and
during this process the main system bus is passed twice. This process can be
repeated for message forwarding.
According to regular flow, when a message arrives, the router will copy it from the
interface memory to the main CPU. The CPU specifies the network ID from the IP
address, consults with the routing table to get the best path to forward the
message, and creates MAC frame suitable for output of the message. The created
MAC frame is copied to the output queue via DMA (Direct Memory Access), and
during this process the main system bus is passed twice. This process can be
repeated for message forwarding.
In the Fast forwarding, cache is used to process messages. After the first message
is forwarded by searching routing table, corresponding exchange information is
generated in the cache, and forwarding of the following same messages can be
realized by directly searching the cache. This practice greatly simplifies the queuing
of IP messages, cuts down the route finding time and improves forwarding
throughput of IP messages. Since the forwarding table in the cache has been
optimized, much quicker searching speed can be obtained.
is forwarded by searching routing table, corresponding exchange information is
generated in the cache, and forwarding of the following same messages can be
realized by directly searching the cache. This practice greatly simplifies the queuing
of IP messages, cuts down the route finding time and improves forwarding
throughput of IP messages. Since the forwarding table in the cache has been
optimized, much quicker searching speed can be obtained.
V2.00 supports Fast forwarding on various high-speed link interfaces, such as
Ethernet, synchronous PPP, frame relay and HDLC.
Ethernet, synchronous PPP, frame relay and HDLC.
Besides, V2.00 also supports fast forwarding when firewall is configured.
Fast forwarding implemented via V2.00 contains the following features:
■
Support fast forwarding on all types of high-speed link interfaces, including
Ethernet, synchronous PPP, frame-relay and HDLC etc.
Ethernet, synchronous PPP, frame-relay and HDLC etc.
■
Provide fast forwarding when the normal firewall is configured.
■
Provide fast forwarding when the ASPF firewall is configured.
■
Support fast-forwarding on the virtual tunnel interface of GRE.
■
Improve packets forwarding efficiency greatly.
Table 453 Configuring TCP attributes
Operation
Command
Configure syn timer time for TCP
connection establishment
connection establishment
tcp timer syn-timeout time-value
Restore syn timer time for TCP connection
establishment to default value
establishment to default value
undo tcp timer syn-timeout
Configure FIN_WAIT_2 timer time of TCP
tcp timer fin-timeout time-value
Restore FIN_WAIT_2 timer time of TCP to
default value
default value
undo tcp timer fin-timeout
Configure Socket receiving/sending buffer
size of TCP
size of TCP
tcp window window-size
Restore Socket receiving/sending buffer
size of TCP to default value
size of TCP to default value
undo tcp window-